JP 2003-148314 A, published by the Japan Patent Office in 2003, proposes an engine automatic stopping device that automatically stops an internal combustion engine when a predetermined condition is established during vehicle travel.
This prior art reference teaches that when a battery capacity is lower than a predetermined value, automatic stopping of the engine is prohibited. Further, this prior art reference teaches that in order to increase opportunities for automatically stopping the internal combustion engine, the internal combustion engine is automatically stopped after the predetermined condition is established not only while the vehicle is stationary but also while the vehicle is traveling.
A battery capacity at which automatic stopping of the internal combustion engine is permitted is set in consideration of an engine start performance and an electrical equipment performance during engine restarting.